page_title: Grumman G-21 Goose
section_title: Variants
hierarchical_section_title: Grumman G-21 Goose / Variants
caption_attribution_description: English: Kaman K-16B 04351 tilt-wing aircraft converted from Grumman JRF-5 Goose
context_page_description: The Grumman G-21 Goose is an amphibious flying boat designed by Grumman to serve as an eight-seat "commuter" aircraft for businessmen in the Long Island area. The Goose was Grumman's first monoplane to fly, its first twin-engined aircraft, and its first aircraft to enter commercial airline service. During World War II, the Goose became an effective transport for the US military, as well as serving with many other air forces. During hostilities, the Goose took on an increasing number of combat and training roles.
context_section_description: G-21
  The original production version, these were powered by two 450-hp (336-kW) Pratt & Whitney Wasp Junior SB engines, at 7,500 lb (3,400 kg) gross weight, with six passengers, and  12 were built, all converted to G-21A standards.
  G-21A
  Increased in gross weight (8,000 lb (3,636 kg)), 30 of these were built.
  G-21B
  Built as export coastal patrol flying boats armed with .30 cal machine gun in bow and dorsal hatches and two 100-lb (45-kg) bombs underwing, 12 were built for Portuguese Naval Aviation.
  G-21C
  Conversion by McKinnon Enterprises, these were re-engined with four 340-hp (254-kW) Lycoming GSO-480-B2D6 air-cooled, geared, and supercharged flat-six engines and fitted with retractable wingtip floats, a fiberglass "radar" nose, a one-piece "wraparound" windshield, and "picture" (enlarged) cabin windows; gross weight increased to 12,499 lb (5,669 kg) as result of internal structural reinforcements. Two were converted as piston-powered models G-21C (serial nos. 1201 and 1202) in 1958–1959, and two other airframes subsequently were converted in 1968, but with two 550-shp (579-eshp, 432-kW) Pratt & Whitney Canada PT6A-20 turboprops per STC SA1320WE as G-21C "Hybrids" (serial nos. 1203 and 1204). Two G-21C "Hybrids" were actually identical to the later 10,500-lb model G-21E, but they were never certified as such.
  G-21D
  One G-21C was further converted by McKinnon with an extended bow section marked by two extra windows on each side and accommodating another four passengers (serial no. changed from 1201 to 1251 in conjunction with recertification as model G-21D in June 1960.) In 1966, it was re-engined with two 550-shp (579-eshp, 432-kW) PT6A-20 turboprops and fitted with revised Alvarez-Calderon electric flaps in accordance with STC SA1320WE, retaining the G-21D designation, but subsequently identified as the McKinnon "Turboprop Goose".
  G-21E
  A fully certified new model, it was based on simplified turbine conversion of McKinnon model G-21C, with 550-shp PT6A-20 engines (680-shp Pratt & Whitney Canada PT6A-27 engines optional) and more fuel, but without all of the structural reinforcements of the G-21C. at 10,500 lb (4,763 kg) gross weight. One was converted (serial no. 1211).
  G-21F
  A conversion by Fish and Wildlife Service in Alaska (using McKinnon engineering data) with 715-shp (533-kW) Garrett TPE331-2UA-203D turboprops, one was converted, but the FWS model "G-21F" was never approved by the FAA and the one example  built was inexplicably recertified as a supposedly modified McKinnon G-21G in spite of the fact that it was not built by McKinnon nor ever conformed to the model G-21G type design.
  G-21G
  The final McKinnon conversion also was fully certified as a new model with 680-shp PT6A-27 engines, 586 US gal of fuel, and 12,500 lb gross weight. Two were converted (serial nos. 1205 and 1226).
  Kaman K-16B
  An experimental tilt wing aircraft, it used the fuselage of a JRF-5 and was powered by two General Electric YT58-GE-2A engines; one was built but unflown.
  XJ3F-1
  The prototype eight-seat utility amphibious plane, it was built for the U.S. Navy; one was built in 1938.
  JRF-1
  A production version of XJ3F-1, five were built for the U.S. Navy.
  JRF-1A
  Similar to the JRF-1, but with target towing gear and camera hatch added, these five were built for the U.S. Navy.
  JRF-2
  A version for the U.S. Coast Guard, these had provisions for carrying stretchers; seven were built.
  JRF-3
  Similar to the JRF-2, these were  fitted with autopilot and deicing boots on the wing leading edges to aid operations in Arctic. Three were built for the Coast Guard.
  JRF-4
  Similar to the JRF-1A, these could carry two depth bombs under wing. Ten were built for the Navy.
  JRF-5
  A major production version, these incorporated bomb racks from the JRF-4, target towing and camera gear from the JRF-1A, and deicing gear from JRF-3; 184 were built. In 1953, a modified JRF-5 was used to test the landing and takeoff characteristics of hydroskis for the U.S. Navy.
  JRF-5G
  These 24 JRF-5s were transferred to the US Coast Guard.
  JRF-6B
  A navigation trainer, these were purchase
caption: The sole Kaman K-16B tilt-wing STOL research aircraft
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